Device for opening a tubular bag and its application

ABSTRACT

Device for opening a tubular bag with a blade attached to an inserting tube, wherein the blade is equipped with at least one edge for lancing the tubular bag and with at least one edge for cutting the tubular bag and the shape of the blade is aligned to the inner wall of the outlet for the material contained in the bag.

The invention concerns a device for the opening of a tubular bag andalso for its application.

BACKGROUND OF THE INVENTION

In the dental field, particularly, pastes of varying consistencies areoffered in tubular bags with increasing frequency. In doing so it isnecessary to guarantee a simple, clean and safe application for theconsumer.

For this purpose the tubular bags are combined with opening mechanismsas have been described already in EP 787 655 (=U.S. Pat. No. 6,012,610),EP 1 121 195 (=U.S. Pat. No. 6.394.643), EP 1 227 049 (=US2002/0113089). However, the known mechanisms have certain disadvantagesdepending on the consistency of the products in these tubular bags.

EP 787 655 describes a device, wherein the bag stretches out underpressure beyond its original shape, before it bursts due to a devicearranged behind the top plate. The disadvantage of this system,particularly in the case of multi-component paste systems, is that apaste can be held back temporarily until this bag bursts open underpartly high pressure and the paste, particularly in the case of freelyflowing pastes, spills over, until the pressure is counter-balanced.Thus this leads to fluctuating mixing ratios, before and after openingboth the components as well.

In the case of pastes with high viscosity and poor ability to flowfreely, a slit-formed bottle opening (A) as mentioned in EP 1 227 049,leads to a high pressure buildup in the bag.

The device described in it creates an opening that is bigger than just aslit. However, in the application of pastes with very high viscosity andvery poor ability to flow freely, the blade 1 (of FIG. 3) attached tothe flow channel causes a disturbed flow resistance in the case of thisenlarged bottle opening.

The task of the invention is to offer a system for tubular bags that iscomfortable for the user, guarantees an even discharge flow from thebeginning and also causes as little flow resistance as possible even inthe case of products with high consistency and high viscosity.

SUMMARY OF THE INVENTION

The task is solved by a device with a blade that is attached to aninserting tube, wherein the switchblade is fitted to the inner wall ofthe outlet for the material contained in the bag for lancing and cuttingthe tubular bag. That is, the shape of the blade follows the wall of theopening and/or represents the wall of the opening. If the outlet iscylindrical, then the blade is preferentially curved such that itconforms to the shape of a cylinder. The invention particularly concernsa device for opening a tubular bag with

-   -   A) an inserting tube with an opening (D) facing the tubular bag        at one end and an outlet at the other end connected to it by        means of a flow channel for the pasty material contained in the        tubular bag.    -   B) a blade attached to the inserting tube.    -   C) wherein the blade is equipped for lancing the tubular bag        with at least one pointed tip facing the tubular bag and at        least one edge connected to the pointed tip for cutting the        tubular bag, characterized by the fact that    -   D) the shape of the blade follows the inner wall of the outlet        for the material contained in the tubular bag.

In a convenient design form one or several bars connected to a toothedwheel in the channel prevent the twisting of the tube when the bag isbeing pierced or is pierced.

DETAILED DESCRIPTION

It proves to be advantageous that the inserting tube and the blade aremade of different materials, namely, the tube is made of a sealingmaterial and the blade is made of a sturdy material. Furthermore, it isadvantageous if the blade has at least two pointed tips that areconnected by a slanting or bent cutting edge. The blade preferentiallycreates a non-linear opening in the foil of the tubular bag by which theresistance for viscous pastes can be kept low.

The blade preferentially has at least two pointed tips that areconnected by a cutting edge. In order to guarantee the optimalfunctioning of the blade, it is necessary to design the blade such thatit is very pointed, sharp-edged and stiff, as would be possible usingsteel or ceramics for instance.

It is possible to design the blade and opening tube out of one unit(combination component). Since the side of the opening tube facing awayfrom the blade must be essentially more flexible and softer in order tobe easily attachable and again removable as a plug connection to themixer, and also in order to have a caulking effect, the ‘combinationcomponent’ should be manufactured out of at least two differentmaterials. The piercing tubes described in EP 1 121 195 do not exhibitmaterial combinations of stiff pointed tip and elastic sealing edge oreven their faultless functioning.

Preferred materials for the sealing component are thermoplasticmaterials like polypropylene or polyethylene and the preferred materialsfor the cutting blade are stainless steel, spring steel, light metal,ceramics or thermoplastic with a high elastic modulus,approximately >=3000 MPa.

In order to be applicable also for very viscous, resistant pastes, theopening pricked into the foil should be as large as possible, the flowchannel should be designed with the largest possible cross-section areaand its surface touching the product should be as small as possible forreduction in friction.

Since normally the length and the height of the flow channel arepredetermined by the necessary compatibility to the existing systems,the required characteristics are guaranteed above all by the shape andseat of the opening blade.

Since the blade is designed such that it is an integral part of the flowchannel wall, and also causes an end-to-end incision that is not linearin the foil, the frictional resistance (viscous drag) of the pastesdrops conspicuously. This represents an appropriate advantage as opposedto the blades that are arranged such that they obstruct the flow of theproduct.

The cut foil piece is furthermore conveniently connected to the bag andis placed at the wall of the outlet channel by the product flow.

The cut surface can be L-, V-, or U-shaped, or semicircular to almostcircular. The smallest press-out strength while simultaneously avoidingthe foil parts from getting into the product—when the bag is opened—canbe achieved if the incision is ¾-circular.

Through this the press-out strength of a paste (viscosity ofapproximately 500 Pa s) drops from 4000-5000 N to approximately 2000 Nwith a linear slit and the blade arranged in the flow channel.

The structural design of the blade has proved to be optimal if the bladehas at least two pointed tips for piercing the foil that are connectedby the slanting and/or curved blade edge.

In order to avoid an unchecked tear propagation of the foil, both thepointed tips of the blade must be advantageously designed

-   at the end of the cutting edge-   at the side away from the cutting edge-   with an angle of at least 180° to the piercing direction.

The pointed tip should not exceed an angle of 45° in order to functionefficiently.

It is functionally convenient to maintain the wall thickness of thecutting edge below 0.5 mm.

An anti-twist device is necessary to avoid the blade from gettingtwisted when or after the bag is pierced. This is ensured when at leastone or several bars are affixed to the tube that engage a toothed wheelaffixed to the bottle cap in the channel if the tube is inserted.Conversely, the toothed wheel can even be arranged in the tube and thebar/s can be arranged in the channel. In the absence of an anti-twistdevice, in certain circumstances in the pierced state, a part of the bagfoil can be separated by a rotary motion of the tube.

For products with extremely high consistencies (kneadable) it isnecessary that the bag is opened by the outlet channel to the maximumpossible cross-section diameter by slitting and piercing the bag,expanding the hole and even punching out the foil. However if this iscarried out by the user by means of a separate tool, the desiredconvenience of the system is lost. In addition, the foil parts can getinto the product.

The opening function can also be coupled with a closing function, sothat a device is developed for the opening and resealing of a tubularbag with a blade affixed to a plug and a sealing element. In doing sothe plug and the blade are preferentially made of different materials,namely, the plug is made of a sealing material and the blade is made ofa sturdy material.

It has proved to be practicable to insert the plug in an open positionduring the manufacturing process in the outlet channel that acts as anopening mechanism and also as a plug for the storage time and transport.The end user must then simply remove the plug and then has a productthat is open and ready for use.

However, because the part for lancing the bag must always be pointed,sharp and stiff, the risk of injury by the pointed plug can be avoidedif the bag is pierced during the manufacturing process and subsequentlysealed with a plug without a pointed tip, which then can be pulled offand can be disposed of safely by the user. This would shift theapplication of the device according to the invention at hand completelyto the manufacturer's side.

In this respect the invention concerns also the production andapplication of preopened and resealed tubular bags wherein the foil ofthe bag in the area of the outlet channel is pierced before delivery andresealed with a sealing plug until application, as well as preopenedtubular bags of such a type wherein the foil piece is punched out andremoved before the sealing plug is inserted.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained more closely with the figures:

FIGS. 1 and 2 illustrate the tubular bag and the opening device beforeand after piercing.

FIG. 3 illustrates a device of the state of art technology with aswitchblade with a straight and pointed blade 1.

FIG. 4 illustrates the solution according to the invention at hand witha blade 2 based on a cylindrical shape (top view 10, three quarters of acircle) and two pointed tips 12, and two bars (21) at the tube thatprovide twist protection.

FIG. 5 illustrates the detailed top, front and side view of a blade with2 pointed tips (12).

FIG. 6 illustrates the detailed top, front and side view of a blade with3 pointed tips (12).

FIG. 7 illustrates a preopened tubular bag with a closure part (coreplug) (19) consisting of blade (20) and plug (23).

FIG. 8 illustrates a solution without switchblade and with preopened bag(C) and sealing plug (24).

FIG. 9 illustrates the detailed side view of a toothed wheel (25)affixed to the channel that functions as twist protection.

FIG. 10 illustrates the top view of the channel with the toothed wheel(25).

FIG. 11 illustrates the tubular bag after lancing, wherein the bars (21)engage the toothed wheel (25) in order to prevent twisting.

In FIG. 1 (unopened state) a safety spacer can be seen as attribute 26that is arranged between the edge of the channel 3 and the broader partof the inserting tube 8 for preventing the unintended opening of thedevice.

The blade 2, 6 in (FIG. 4, 5, 6) is introduced through the channel 3(FIG. 2) and is then arranged opposed to EP 787 655 conspicuously infront of the level 4 of the top plate 5.

In order to guarantee the optimal function of this blade 2, 6 it isnecessary to design it such that it is very pointed, sharp-edged andstiff as is possible for example with steel or ceramics.

Since the other side 8 of this opening tube (7,8, FIG. 4) however mustbe essentially more elastic and softer, in order to be easily attachableand again removable as plug-in connection to the mixer and also have acaulking effect, each tube 7, 8 must be manufactured out of at least twodifferent materials. The piercing tubes described in EP 1 121 195 do notexhibit material combinations of stiff pointed tip and elastic sealingedge or even their faultless functioning.

Preferred material for the part 7, 8 are thermoplastic materials likepolypropylene or polyethylene and the preferred materials for the part2, 6 are stainless steel, spring steel, light metal, ceramics orthermoplastic with high elastic modulus.

In order to be applicable also for very viscous, resistant pastes, theopening B that is pricked into the foil should be as large as possible,the flow channel must be designed with a cross-section area that is aslarge as possible and its surface touching the product should be assmall as possible for friction reduction.

Since normally the length and the height of the flow channel arepredetermined by the necessary compatibility to the existing systems,the required characteristics are guaranteed above all by the shape andseat of the opening blade.

Since the blade is designed such that it is an integral part of the flowchannel wall 9, and also causes an end-to-end incision that is notlinear in the foil, the frictional resistance (viscous drag) of thepastes drops considerably. This represents an appropriate advantage asopposed to the blades that are arranged such that they obstruct the flowof the product. (FIG. 3).

The cut surface can be L-, V-, or U-shaped or semicircular to almostcircular (FIG. 4, B, 10).

The smallest press-out strength while simultaneously avoiding the foilparts from getting into the product of an opened bag of such type can beachieved if the incision B is ¾-semicircular 10.

Through this the press-out strength of a paste (viscosity ofapproximately 500 Pa s) drops from 4000-5000 N to approximately 2000 Nwith a linear slit and the blade 1 arranged in the flow channel 11 (FIG.3)

The structural design of the blade has proved to be optimal if the bladehas at least two pointed tips 12, 13 for piercing the foil that areconnected to each other by the slanting and/or bent blade edge 14.

In order to avoid an unchecked tear propagation of the foil 15 (FIG. 2),both the pointed tips 12 must be designed at the end of the cutting edge14 at the side 16 facing away from the cutting edge with an angle 17 ofat least 180° to the piercing direction. The pointed tip 12, 13 shouldnot exceed an angle 18 of 45° in order to function efficiently.

It is functionally convenient to maintain the wall thickness of thecutting edge 14 below 0.5 mm.

An anti-twist device is necessary to avoid the blade from gettingtwisted when or after the bag is pierced. This is ensured when at leastone or several bars 21 are affixed to the tube 7 that engage a toothedwheel 25 affixed to the bottle cap in the channel 3, if the tube isinserted.

Conversely, even the toothed wheel can be arranged at the tube and thebars can be arranged in the channel.

In the absence of an anti-twist device, in pierced state a part of thebag foil can be separated by a rotary motion of the tube.

For products with extremely high consistencies (kneadable) it isnecessary that the bag is opened by the outlet channel to the maximumpossible cross section diameter by slitting and piercing the bag,expanding the hole and even punching out the foil.

However if this is carried out by the user by means of a separate tool,the desired convenience of the system is lost. In addition, through thisthe foil parts can get into the product.

It has proved to be practicable to insert a part 19 (FIG. 7) during themanufacturing process in the outlet channel 22 that acts as an openingmechanism 20 and also as a plug 23 for the storage time and transport.The end user must then simply remove the plug 23 and then has a productthat is open and ready for use.

However because the part for lancing the bag must always be pointed,sharp and stiff, a further advantage can be obtained for the user if therisk of injury by the pointed plug is avoided. This is achieved if thebag is pierced during the manufacturing process and subsequently sealedwith a plug 24 without a pointed tip, which then can be pulled off bythe user and can be disposed of safely.

The inserting tube 7, 8 and the blade 2, 6 are preferentially made ofdifferent materials, namely, the tube is made of a sealing material andthe blade is made of a sturdy material.

Thermoplastic resins can be used as sealing material. The preferredmaterials for the cutting blade are stainless steel, light metal,ceramics or thermoplastic with a high elastic modulus,approximately >=3000 MPa.

In a convenient design form one or several bars 21 at the tube 7connected to a toothed wheel 25 in the channel 3 prevent the twisting ofthe tube when the bag is being pierced or is pierced.

The cut out foil piece 10 is furthermore conveniently connected with thebag 15 and is placed at the wall 9 of the outlet channel 7 by theproduct flow.

The opening function can also be coupled with a closing function, sothat a device is developed for the opening and resealing of a tubularbag 15 with a blade 2, 6 affixed to a plug 19 and a sealing element 23.In doing so the plug (23) and the blade (2, 6) are preferentially madeof different materials, namely, the plug is made of a sealing materialand the blade is made of a sturdy material.

In this respect the invention also concerns the production andapplication of preopened and resealed tubular bags, wherein the foil ofthe bag 15 in the area of the outlet channel 22 is pierced beforedelivery, and resealed with a sealing plug 24 until application; as wellas preopened tubular bags of such a type, wherein the foil piece ispunched out and removed before the sealing plug is inserted.

1. Device for opening a tubular bag comprising A) an inserting tube withan opening adapted to face a tubular bag at one end and an outletconnected to it at the other end via a flow channel for materialcontained in the tubular bag, B) a blade fitted to the inserting tube,C) wherein the blade is equipped with at least one pointed tip forlancing the tubular bag and with at least one edge connected to thepointed tip for cutting the tubular bag and wherein D) the shape of theblade conforms to that of the inner wall of the outlet for the materialcontained in the tubular bag.
 2. Device according to claim 1, whereinthe blade has the shape of a part of a cylinder wall.
 3. Deviceaccording to claim 1, wherein the blade has the form of three quartersof a cylinder wall.
 4. Device according to claim 1, wherein the bladehas at least two pointed tips that are connected by a slanting or bentedge.
 5. Device according to claim 1, wherein the inserting tube is madeof a sealing material and the blade is made of a sturdy material. 6.Device according to claim 5, wherein the inserting tube is made of athermoplastic resin and the blade is made of bent steel.
 7. Deviceaccording to claim 5, wherein the inserting tube is made of athermoplastic resin and the blade is made of light metal.
 8. Deviceaccording to claim 5, wherein the inserting tube is made of athermoplastic resin and the blade is made of ceramics.
 9. Deviceaccording to claim 5, wherein the inserting tube is made of athermoplastic resin with an elastic modulus <=≦2000 MPa and the blade ismade of a thermoplastic resin with an elastic modulus >=≧3000 MPa. 10.Device according to claim 1, comprising at least one bar in the tube anda toothed wheel in the flow channel to prevent the tube from gettingtwisted when the tubular bag is being pierced or has been pierced andthe device is engaged with the bag.
 11. Device according to claim 1,comprising at least one bar in the channel and a toothed wheel in thetube to prevent the tube from getting twisted when the tubular bag isbeing pierced or 3has been pierced and the device is engaged with thebag.
 12. Method of opening a tubular bag with device of claim 1, whereina piece of the tubular bag is cut and remains partially connected withthe bag and is placed by the product flow at the wall of the outletchannel.
 13. Device according to claim 1 disposed as a sealing plug forthe outlet to which the blade is attached at the side facing the tubularbag.
 14. Device according to claim 13, wherein the plug comprises aseparate sealing element for sealing the outlet.
 15. Device according toclaim 13, wherein the plug or the sealing element are made of a sealingmaterial and the blade is made of a sturdy material.
 16. Process for themanufacture of preopened and resealed tubular bags wherein a tubular bagis pierced in the area of its outlet channel with the device of claim 1before delivery and is resealed until application by a sealing pluginserted in the device.
 17. Process according to claim 16, wherein apiece of the tubular bag is punched out and removed before the sealingplug is inserted.